We have very old Xorg version 1.17 in our xorg-kit. which was released in Feb 2015.

In our previous ports-2012 tree (in current branch),  We had Xorg 1.19 which worked flawlessly,
but during conversion to meta-repo and slashing of stable, it seems our xorg version got somehow downgraded from 1.19 to 1.17.

Please note that most major distros (Debian Stretch, Ubuntu 17.04 etc...) already use Xorg 1.19, which supports most of the new GPUs (especially from AMD).